1. Field of the Invention
The present invention relates to a liquid ejection head capable of ejecting liquid contained in a pressure chamber from ejection ports by using energy produced by energy generation elements, and to a liquid ejecting apparatus using the same.
2. Description of the Related Art
An example construction of this kind of liquid ejection head is taken from Japanese Patent Laid-Open No. 2009-39914. A print head (liquid ejection head) 71 as shown in FIGS. 6A and 6B has a print substrate 72 and top plate 73 joined together. The top plate 73 is formed with a plurality of ejection ports 78 arranged in two arrays LA-1, LA-2. The print substrate 72 has supply ports 74A, 74B, 74C formed therein in three supply port arrays LB-1, LC, LB-2. Ink (liquid) supplied from the supply ports 74 (74A, 74B, 74C) flows through cylindrical filters 80 into ink paths 77 formed between path walls 76. The ink in the ink path 77 is heated by an electrothermal conversion element (heater) 79 as an energy generation element to form a bubble, and thereby being ejected from the corresponding ejection port 78. A portion of each ink path 77 between the election port 78 and the heater 79 has a role of a pressure chamber.
Such ink paths 77 in this type of print head 71 can be improved in an ink refilling performance by supplying ink to them from the supply ports 74 (74A, 74B, 74C) on both sides as shown in FIGS. 6A and 6B.
In serial scan type inkjet printing apparatuses (liquid ejecting apparatuses), an image is printed by the print head 71 ejecting ink from the ejection ports 78 according to print data as it moves in a main scan direction crossing the ejection port arrays LA-1, LA-2. To produce a high quality image, the distance between the ejection port arrays LA-1 and LA2 needs to be set at an integer times an image print resolution in the main scan direction. This imposes a limitation on the size in the main scan direction of the supply ports 74B on the supply port array LC, which in turn may force the dimension of the supply ports 74B in a direction perpendicular to the direction of extension of the supply port array LC to be set larger than is required by the ink supply performance, resulting in an increased overall size of the print substrate 72 and therefore an increased size and cost of the print head 71.
In a process of forming the plurality of supply ports 74 (74A, 74B, 74C) in the same print substrate 72 with dry etching, if the supply ports 74 to be etched differ in the opening area, they also differ in an etching rate, taking different times to complete the etch. As a result, the supply ports of small opening areas may be excessively etched, with their openings becoming larger than their intended sizes or shaped like a notch. For this reason, in forming the plurality of supply ports 74 in the same board 74 with dry etching, the supply ports need to be designed to have almost equal opening areas. When the supply ports 74B are set large in a direction perpendicular to the direction of extension of the supply port array LC to make their opening area large enough to maintain their ink supply performance, other supply ports 74A, 74C also need to be set correspondingly large in the opening area. This, however, will likely increase the size of the board 72, resulting in increased size and cost of the print head 71.